Digital cameras generally include a light-sensitive sensor, on which an image is imaged by means of optics. The incident light is converted into a charge in the sensor (for example, a charge-coupled device (CCD) sensor or a CMOS sensor), which is converted into a voltage value at a further stage. The voltage generated in this fashion is proportional to the incident quantity of light.
For detecting and representing a color image, the individual colors are detected selectively. For example, a three-chip camera can be used to separate the light into the corresponding red, green, and blue components with a beam splitter prism. The three-chip camera includes three sensors (or chips). Each of the beams separated from the prism is guided to a separate sensor, and each of the sensors represents the red, green, and blue components, respectively, of the incident light as separate voltage signals.
As another example, a one-chip camera can be used to detect a color image. The one-chip camera includes only one sensor (or chip); therefore, the color-selective detection of the incident light is obtained by color filters disposed on the pixels. In this fashion, different, microscopically small filters are disposed on the individual pixels, thus ensuring that each pixel is exposed to only one defined color component. In the one-chip camera, neighboring pixels are provided with different color filters in order to be able to regenerate the actual color of the image area in a downstream processing step. The downstream electronics calculates a color value for the respective area from the color components of the directly neighboring pixels.
The color temperature of operating lamps can be adjusted to improve the distinguishability of different types of tissue. The white light then tends to have components in a range from red to blue. If a video camera were used to transmit the image from the operating area, the resulting image would have a reddish to bluish color in dependence on the setting of the operating lamp.